#使用函数
def print_models(unprinted_designs,completed_models):
    while unprinted_designs:
        current_design=unprinted_designs.pop()
        print(f"Printing model:{current_design}")
        completed_models.append(current_design)

def show_completed_models(completed_models):
    print("\nThe following models have been printed: ")
    for completed_model in completed_models:
        print(completed_model)

unprinted_designs=['phone case','robot pendant','dodecahedrom']
completed_models=[]
print_models(unprinted_designs[:],completed_models)
#切片表示法能创建列表的副本，这样原始列表的内容就得以保存